Many materials, and notably a large range of important pharmaceutical preparations, are subject to accelerated degradation by temperature and other environmental conditions. In particular, a number of commonly prescribed medications are temperature and light unstable. The best known is glyceryltrinitrate. Others include benzodiazepines, prochlorperazine, penicillin, pseudoephedrine, promethazine, prednisolone and captopril.
The manufacturers of glyceryltrinitrate recommend that the tablets be stored at temperatures of less than 25.degree. C. and protected from light. The standard brown glass bottle falls far short of these criteria; for example these types of containers reach an internal temperature of 25.degree. C. within 20 minutes of removal from a refrigerator, and the temperature of tablets carried in a shirt or trouser pocket rapidly reaches 35.degree. C.
There have been two previous attempts to provide an insulated container for heat-sensitive materials. Southwick (U.S. Pat. No. 3,472,568; 1969) describes a fibre container having an inner insulating layer with a removable inner receptacle, the insulating layer being surrounded by a hard exterior shell with detachable top. The novel feature of this invention was a humidity control device. This invention was not directed specifically at protection of pharmaceuticals. Lowe (U.S. Pat. No. 4,054,208; 1977) describes a container for medicinal tablets, capsules or pills, to be carried on the person, consisting of two concentric cylindrical tubes, the inner tube being of translucent amber-coloured plastic or glass, separated from an outer transparent tube by an air space. This invention was intended to protect pharmaceutical products from body heat, light, and moisture, as well as from mechanical damage. No insulation or heat-protective device other than the airspace was incorporated into the invention.
It is an object of this invention to overcome the defects of the prior art by providing a container with superior protective properties, particularly against the deleterious effects of heat.